J 9 5] Journal of the Mitchell Society. 63 



soap was used and retained favor; quassi, hellebore and 

 tobacco were standard insecticides as early as 1855. Sulphur 

 was used for the mildews and bluestone for wheat smut. 



The last twenty years of the nineteenth century mark the 

 beginning of a new epoch in plant protection. For this there 

 are three reasons: first, the increased aggressiveness of a 

 certain fungous disease, the grape mildew, in Europe; sec- 

 ond, the rapid spread of the potato bug, somewhat pedanti- 

 cally termed the Colorado beetle, and, third, resulting from 

 these two, revolutionary changes in materials and methods 

 for treating plant diseases, both fungous and insect, in the 

 new world and in the old. It is a matter not entirely without 

 interest that the revolution in European methods may be 

 definitely traced to typical American aggressiveness, inas- 

 much as the activity arousing fungus was of American 

 importation. 



In Europe the invasion of the downy mildew of the grape 

 in 1878 was unchecked by the most vigorous fungicides then 

 used. All are familiar with the story of the great benefit 

 conferred upon humanity through the predatory habits of the 

 French boys in the vineyards that produce the famous Bor- 

 deaux wines. The rows lying nearest the roadway were 

 sprinkled with verdigris or a mixture of lime and bluestone, 

 to give the impression that the fruit was poisoned. In 1882 

 Millardet, of the faculty of the sciences, noticed that the 

 vines thus treated held their leaves while others succumbed 

 to the mildew. He ascribed this effect to its proper cause, 

 and conducted carefully systematized experiments, which 

 resulted in giving to the world bouillie bordelaise, Bordelaiser 

 Bruhe, or Bordeaux mixture, a proved fungicide of great effi- 

 ciency; one that has not yet been surpassed. 



In the new world the extension of the potatoe belt west- 

 ward connected the eastern potato belt with the region of the 

 native food plant of the familiar potato bug. Finding the 

 potato plant a more abundant and wholesome food than the 

 wild solonaceous plants that it had formerly fed upon, the 



